<!DOCTYPE html>
<html>

<head>
    <base href="$FLUTTER_BASE_HREF">

    <meta charset="UTF-8">
    <meta content="IE=Edge" http-equiv="X-UA-Compatible">
    <meta name="description" content="A new Flutter project.">

    <!-- iOS meta tags & icons -->
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black">
    <meta name="apple-mobile-web-app-title" content="myflutter">
    <link rel="apple-touch-icon" href="icons/Icon-192.png">

    <title>myflutter</title>
    <link rel="manifest" href="manifest.json">
</head>

<body>
    <!-- This script installs service_worker.js to provide PWA functionality to
       application. For more information, see:
       https://developers.google.com/web/fundamentals/primers/service-workers -->
    <script>
        var serviceWorkerVersion = null;
        var scriptLoaded = false;

        function loadMainDartJs() {
            if (scriptLoaded) {
                return;
            }
            scriptLoaded = true;
            var scriptTag = document.createElement('script');
            scriptTag.src = 'main.dart.js';
            scriptTag.type = 'application/javascript';
            document.body.append(scriptTag);
        }

        if ('serviceWorker' in navigator) {
            // Service workers are supported. Use them.
            window.addEventListener('load', function() {
                // Wait for registration to finish before dropping the <script> tag.
                // Otherwise, the browser will load the script multiple times,
                // potentially different versions.
                var serviceWorkerUrl = 'flutter_service_worker.js?v=' + serviceWorkerVersion;
                navigator.serviceWorker.register(serviceWorkerUrl)
                    .then((reg) => {
                        function waitForActivation(serviceWorker) {
                            serviceWorker.addEventListener('statechange', () => {
                                if (serviceWorker.state == 'activated') {
                                    console.log('Installed new service worker.');
                                    loadMainDartJs();
                                }
                            });
                        }
                        if (!reg.active && (reg.installing || reg.waiting)) {
                            // No active web worker and we have installed or are installing
                            // one for the first time. Simply wait for it to activate.
                            waitForActivation(reg.installing || reg.waiting);
                        } else if (!reg.active.scriptURL.endsWith(serviceWorkerVersion)) {
                            // When the app updates the serviceWorkerVersion changes, so we
                            // need to ask the service worker to update.
                            console.log('New service worker available.');
                            reg.update();
                            waitForActivation(reg.installing);
                        } else {
                            // Existing service worker is still good.
                            console.log('Loading app from service worker.');
                            loadMainDartJs();
                        }
                    });

                // If service worker doesn't succeed in a reasonable amount of time,
                // fallback to plaint <script> tag.
                setTimeout(() => {
                    if (!scriptLoaded) {
                        console.warn(
                            'Failed to load app from service worker. Falling back to plain <script> tag.',
                        );
                        loadMainDartJs();
                    }
                }, 4000);
            });
        } else {
            // Service workers not supported. Just drop the <script> tag.
            loadMainDartJs();
        }
    </script>
</body>

</html>